Nonlinear behaviors of cosmological inhomogeneities are studied in the anti-Newtonian or long-wavelength approximation. They consist of a standard fluid and inflationary matter. The latter is an inflationary fluid or a scalar field. After the initially dominant local anisotropy has decreased, they become quasiisotropic. If the density of the standard fluid is dominant at this stage, the inhomogeneities grow with time, but, as the density of the inflationary matter increases, it is shown that the growth is gradually prevented and finally they decay. After the inflation they again grow due to the irregular spatial curvature. The generality of the solutions is also discussed.

• Received 1 June 1994

DOI:https://doi.org/10.1103/PhysRevD.50.7216